This may look more like a chemistry set than a coffee maker, but the vac pot (also known as vacuum pot or siphon maker) is a great way to brew excellent coffee. It doesn’t use paper filters, so the end product is 100% pure coffee flavor that’s crisp and delicious. And it’s a great way to entertain guests with an after dinner cup of coffee! Continue reading to learn the basics, and check out my video post on vac pot brewing.

While some people suspect the vac pot is a geeky new toy for coffee enthusiasts, this method of brewing has actually been around since the early 1800s. (Mark Prince, the brains behind CoffeeGeek.com actually has a great history on vacuum brewing here.) For serious coffee folks, this is a fun way to enjoy a crisp, clean cup of coffee. In addition to its taste, an attraction to vac pot brewing is the brewer’s heightened control of the variables as compared to other methods. 

The majority of vac pots are either stove top or table top. Stove top pots rely on the heat from an electric or gas burner located beneath the lower chamber. Table top pots use a self-contained heating element, such as an alcohol burner. Both achieve the same effect, and the choice to use one over the other is usually based on aesthetics or the need for portable brewing.  

Another variation is the electric vac pot. A popular example is the Bodum Electric Santos. This model automates much of the brewing at the press of a button. The downside is the brewer has less control over the variables, which is the very reason many enthusiasts get into vac pot brewing in the first place. 

Using a vac pot doesn’t have to be intimidating. It’s easy enough to simply make a good cup of coffee, but the possibilities are virtually limitless. Vac pots are also available at a modest introductory price range, making vac pot brewing accessible for all coffee lovers. 

Disclaimer: there are slight variations for the equipment described below, and brewers may disagree with the exact “right” way to use a vac pot. This post is a general overview of common equipment and methods used. 

An overview of the basic equipment:

Lower (vacuum) chamber - this glass chamber contains the water during the beginning of the brew cycle. It rests on or just above a heating source - typically stove top or an alcohol burner - and is the location of the water expansion/contraction (the “vacuum”) that allows this method of brewing to work. Once the brew cycle is complete, this is also where the end product - delicious coffee - is contained.

Upper (brewing) chamber - the upper chamber has a rubber gasket that connects both chambers while a glass tube extends down into the lower chamber. This tube allows the water to be pushed upward where it mixes with the ground coffee, and then back down as the ground coffee is filtered and remains in the upper chamber. 

Filter - the filter, typically a plastic disk of sorts, is connected to the upper chamber tube by a spring that applies enough force to keep coffee grounds from traveling downward, but not so much to restrict the flow of water (and eventually coffee) from passing.

How does it work?

When a heat source is applied to the lower chamber, the water produces water vapor. The subsequent expansion of water vapor means an outlet is necessary (or else the chamber would explode!) so the water is forced upward through the tube and into the upper chamber. 

The water mixes with coffee grounds in the upper chamber, steeping the coffee and extracting its solubles (the chemistry of coffee - lipid oils, caffeine, sugars, blah blah blah). At this time the heat source is also removed. Without it, the vapor in the lower chamber turns back into water, which creates a vacuum that pulls the steeping coffee down through the chamber tube and into the lower chamber. What remains in the upper chamber are wet, steaming, spent coffee grounds.

The upper chamber is then removed and the coffee is ready to be served!